UMR 8640 : Electrochemistry

Monitoring and Quantifying the Passive Transport of Molecules Through Patch–Clamp Suspended Real and Model Cell Membranes

Transport of active molecules across biological membranes is a central issue for the success of many pharmaceutical strategies. Herein, we combine the patch-clamp principle with amperometric detection for monitoring fluxes of redox-tagged molecular species across a suspended membrane patched from a macrophage.

Mass transport at infinite regular arrays of microband electrodes was investigated theoretically and experimentally in unstirred solutions. Even in the absence of forced hydrodynamics, natural convection limits the convection-free domain up to which diffusion layers may expand. Hence, several regimes of mass transport may take place according to the electrode size, gap between electrodes, time scale of the experiment, and amplitude of natural convection. They were identified through simulation by establishing zone diagrams that allowed all relative contributions to mass transport to be delineated. Dynamic and steady-state regimes were compared to those achieved at single microband electrodes. These results were validated experimentally by monitoring the chronoamperometric responses of arrays with different ratios of electrode width to gap distance and by mapping steady-state concentration profiles above their surface through scanning electrochemical microscopy.

Nanoelectrodes for Determination of Reactive Oxygen and Nitrogen Species inside Murine Macrophages

Reactive oxygen and nitrogen species (ROS and RNS) produced by macrophages are essential for protecting a human body against bacteria and viruses through digestion of ingested bodies in specific vacuoles. However, the issue concerning the potential leakage of ROS/RNS from vacuoles has been raised as a tentative explanation to some illness (e.g., gout). The purpose of this work was to investigate quantitatively and kinetically this issue.

Biomedical properties of Egyptian black makeup were revealed by amperometry at single cells. Using ultramicroelectrodes, new insights were obtained into the biochemical interactions between lead(II) ions and cells, which support the ancient medical use of sparingly soluble lead compounds.